I thought the "SMALL_RECT"-structure is already included in windows.h.
But I tried it anyway and it even highlight "Left" and "Right" in struct as before.
I'm using Visual Studio 2013 and Left and Right is also coloured purple if this helps.
SMALL_RECT is defined in <wincon.h>, automatically added by <windows.h> (per MSDN). https://msdn.microsoft.com/en-us/library/windows/desktop/ms686311%28v=vs.85%29.aspx
Trying explicitly including <wincon.h> after your <windows.h> include. A big reach, but worth a try.
Are you adding any 3rd party libraries that might redefine SMALL_RECT?
I don't use VS2013 so I'm stumped why you are getting this error.